Implantable cardiac stimulation system and method for monitoring diastolic function

• US 6,810,284 B1
• Filed: 11/21/2001
• Issued: 10/26/2004
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Bradley, Kerry
• Primary Examiner(s): Schaetzle, Kennedy
• Assistant Examiner(s): DROESCH, KRISTEN L
• Application Number:
  US09/996,306
• Time in Patent Office: 1,070 Days
• Field of Search: 600/508, 600/509, 600/510, 600/513, 607/9, 607/27-28
• US Class Current: 600/510
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

A cardiac stimulation device and method perform a diastolic function test during which an amplitude-based feature of an evoked response is determined for a number of AV or PV delay settings. Stimulation operating parameters may be adjusted in response to a detected change in diastolic function. The diastolic function test may be repeated periodically with results stored in memory for later downloading to an external device allowing a physician to monitor the diastolic response to a selected treatment.

Claims

1. A method for monitoring diastolic function in a cardiac stimulation device, the method comprising:

determining peak negative depolarization amplitudes following the delivery of ventricular stimulation pulses at various ventricular filling times;

determining a slope of a relationship between the peak negative depolarization amplitudes and the various ventricular filling times;

comparing the slope with a stored value to indicate diastolic function of the heart.

3. The method according to claim 1, further comprising verifying a predetermined state of activity prior to initiating the diastolic function test.

4. The method according to claim 3, wherein verifying the predetermined state of activity comprises verifying a state of rest.

5. The method according to claim 3, further comprising verifying a predetermined posture prior to initiating the diastolic function test.

6. The method according to claim 5, wherein verifying the predetermined posture comprises verifying a supine position.

2. A method for performing a diastolic function test in a cardiac stimulation device, the method comprising:

determining paced depolarization integral values following ventricular stimulation pulses delivered at various ventricular filling times;

calculating a slope of a relationship between the paced depolarization integral values and the ventricular filling times;

comparing the slope with a stored value to indicate the current diastolic function of the heart.

7. The method according to claim 2, further comprising ensuring that the ventricular stimulation pulses are sufficient to capture the ventricle.

8. The method according to claim 7, wherein ensuring that the ventricular stimulation pulse will capture the ventricle comprises setting a ventricular stimulation pulse output to a predetermined level known to exceed a ventricular capture threshold.

9. The method according to claim 2, further comprising adjusting a ventricular stimulation timing parameter for controlling the ventricular filling times.

10. The method according to claim 9, wherein adjusting the ventricular stimulation timing parameter comprises adjusting at least one of:

a first atrial-ventricular delay (AV delay) that follows an atrial stimulation pulse;

a second atrial-ventricular delay (PV delay) that follows a sensed atrial P-wave; and

a ventricular escape interval.

11. The method according to claim 10, further comprising applying each ventricular stimulation timing parameter a predetermined number of times.

12. The method according to claim 10, wherein acquiring the paced depolarization integral comprises, for each ventricular stimulation timing parameter, acquiring a predetermined number of paced depolarization integrals.

13. The method according to claim 12, wherein acquiring a predetermined number of paced depolarization integrals comprises acquiring eight paced depolarization integrals for each ventricular stimulation timing parameter.

14. The method according to claim 12, further comprising verifying a stable heart rhythm within a predetermined rate range, prior to acquiring the paced depolarization integrals.

15. The method according to claim 14, wherein acquiring a paced depolarization integral comprises:

setting a detection window following the delivery of the ventricular stimulation pulse;

setting a unipolar sensing electrode configuration for sensing a ventricular cardiac signal;

sampling a ventricular cardiac signal during the detection window; and

integrating the ventricular cardiac signal samples.

16. The method according to claim 15, further comprising integrating ventricular cardiac signal samples having a magnitude greater than a predetermined integration baseline.

17. The method according to claim 15, further comprising determining if fusion is suspected following the delivery of the ventricular stimulation pulse;

and

if fusion is suspected, excluding the paced depolarization integral from calculating the average paced depolarization integral.

18. The method according to claim 15, further comprising storing the slope of the relationship.

19. The method according to claim 18, further comprising downloading stored slope data to an external device.

20. The method according to claim 15, further comprising adjusting a stimulation operating parameter if a worsening in diastolic function is detected.

21. A cardiac stimulation device for performing a diastolic function test, comprising:

at least one electrode that senses cardiac activity;

a ventricular pulse generator that selectively delivers a ventricular stimulation pulse;

a controller, connected to the ventricular pulse generator and the electrode, the controller being operative to determine an amplitude-based feature of an evoked response following a ventricular stimulation pulse, and that calculates a slope of a relationship between the amplitude-based feature and ventricular filling times; and

circuitry that compares the slope with a stored value to indicate diastolic function of the heart.

22. The device according to claim 21, further comprising a physiological sensor that verifies a predetermined state of activity prior to initiating the diastolic function test.

23. The device according to claim 22, wherein the predetermined state of activity is a state of rest.

24. The device according to claim 22, further comprising a physiological sensor that verifies a predetermined posture prior to initiating the diastolic function test.

25. The device according to claim 24, wherein the predetermined posture is a supine position.

26. The device according to claim 22, wherein the controller ensures that a ventricular stimulation pulse will capture the ventricle.

27. The device according to claim 22, wherein the controller adjusts a ventricular stimulation timing parameter for controlling the ventricular filling times.

28. The device according to claim 27, wherein the ventricular stimulation timing parameter comprises any one or more of:

a first atrial-ventricular delay (AV delay) that follows an atrial stimulation pulse;

a second atrial-ventricular delay (PV delay) that follows a sensed atrial P-wave; and

a ventricular escape interval.

29. The device according to claim 21, further comprising a telemetry circuit that downloads stored slope data to an external device.

30. The device according to claim 21, wherein the amplitude-based feature comprises at least one of a paced depolarization integral and peak negative amplitude.

31. A cardiac stimulation device for performing a diastolic function test, comprising:

means for selectively delivering a ventricular stimulation pulse;

means for acquiring an amplitude-based feature of an evoked response following ventricular stimulation pulses delivered at various ventricular filling times;

means for calculating a slope of a relationship between the amplitude-based feature and the ventricular filling times; and

means for comparing the slope with a stored value to indicate the diastolic function of the heart.

32. The device according to claim 31, further comprising means for verifying a predetermined state of activity prior to initiating the diastolic function test.

33. The device according to claim 32, wherein the predetermined state of activity comprises a state of rest.

34. The device according to claim 32, further comprising means for verifying a predetermined posture prior to initiating the diastolic function test.

35. The device according to claim 34, wherein the predetermined posture is a supine position.

36. The device according to claim 32, wherein the means for acquiring the paced depolarization integral ensures that a ventricular stimulation pulse will capture the ventricle.

37. The device according to claim 32, wherein the means for acquiring the paced depolarization integral adjusts a ventricular stimulation timing parameter for controlling the ventricular filling times.

38. The device according to claim 37, wherein the ventricular stimulation timing parameter comprises any one or more of:

a first atrial-ventricular delay (AV delay) that follows an atrial stimulation pulse;

a second atrial-ventricular delay (PV delay) that follows a sensed atrial P-wave; and

a ventricular escape interval.

39. The device according to claim 31, further comprising means for downloading stored slope data to an external device.